Main Bearings

Post by **SvMinor** » Tue Nov 03, 2009 11:54 pm

Got a new main bearing kit today tried to remove the front shell cover with engine in the car.cant get it off,got the 2 bolts out ok but thats it.tried tapping with a plastic hammer,cover wont shift,and theres 3 of them!O S*!t
Help!
Can the main bearings be fitted with engine still in the car.
Cheers Mark

Post by **PSL184** » Wed Nov 04, 2009 12:00 am

Only the centre main will come off easily. The front one will need you to remove the front cover to get access and the rear is an engine out job.

Post by **MikeNash** » Wed Nov 04, 2009 6:56 am

Mark,
I recently replaced the front and middle mains but not there rear. The caps come off with a bit of sideways tapping with the plastic hammer but you'll find the bearing shells themselves a little tricky esp the upper ones in the block. The lower ones you'll be able to pick out although with luck they'll come off in the bearing caps. For the uppers you'll need a short CLEAN split-pin on which you bend over the tangs at right angles to each other. Insert the prepared split-pin into the oil hole in the crank and rotate the crank and split-pin will go round and the upper shell will be pushed round and you can pick it off. You put the new one in the same way. Of course, the bent over tangs need to be no "thicker" than the thickness of the shell. Its actually easier than it sounds.
For the rear mains, I found on my 1098 I couldn't wriggle out the main bearing cap, so failure there I'm afraid; it needs the the back plate off! But I'm sure I've heard of it being done. MikeN.

Post by **MarkyB** » Wed Nov 04, 2009 8:34 am

You can use the edge of the bottom shell to get the top one moving.
Once you have the front and middle mains out poke the top thrust bearing out (on the sides of the centre main).
Lever the crankshaft forwards with the handle of a hammer or the like.
This should give enough clearance to get the rear main off.
Let us know how you get on.

Post by **bmcecosse** » Wed Nov 04, 2009 9:11 am

If you disturb the thrust bearings - make ABSOLUTELY SURE you put them back in right way round. There is no better way to destroy both block and crank - in about 10 seconds - than to run the engine with incorrect thrusts. The rear main cannot be changed -front needs the two little screws under the timing gear taking out - and even then you will damage the gasket -so best to take the front plate off and fit a new gasket. Of course the front plate carries the engine mounts - so you will have to struggle with them too - best to take one of the 'towers' off. To get access - you may want to take the radiator and front panel off - and of course you will need to loosen the starter dog! generally - if the main bearings need renewing - the crank shaft will be worn and a re-grind is called for. Unless the crank is utterly smooth and has no detectable 'ridge' in the centre of each journal - where the oil groove in the shell lives - there is no point fitting new shells without a regrind.

Post by **bigjohn** » Wed Nov 04, 2009 10:56 am

just take the engine out and do the job propperly

Post by **bmcecosse** » Wed Nov 04, 2009 10:59 am

I'm afraid it's heading that way! Do you have a picture of the centre-main shells Mark ? That's usually the one with the worst wear.

Post by **stevey** » Wed Nov 04, 2009 1:04 pm

seems to be an engine out job and then strip it completely.

Post by **PSL184** » Wed Nov 04, 2009 4:57 pm

I've never tried MarkyB's method of removing the thrust washers so I cannot comment other than to say it is not a big job to pull the engine out and do the bearings in a comfortable manner ie standing at the bench or on an engine frame, however, lying on your back looking up at the oil dripping bottom end is a pain in the bum

Post by **MarkyB** » Wed Nov 04, 2009 6:03 pm

I'll readily accept bmcecosse's caveat about the condition of the crankshaft.
If it's scored up, engine out and give it the full Monty.
Thrust washers go in with the copper face to the crankshaft. It may well be a disaster to put them in the wrong way round, but doing that isn't a function of whether the engine is in or out so a bit of a red herring.

The timing cover needs to come off to remove the screws that hold the front main so you might as well do the timing chain while you are at it.
Highly recommended to take the front panel with radiator attached off.

Taking the engine out involves disturbing lots of stuff and some heavy lifting or manoeuvring.

If you aren't happy with how the job is going you can refit the sump and go to plan B, remove the engine.

Post by **bmcecosse** » Wed Nov 04, 2009 7:05 pm

The point is -when lying on back - with oil dripping etc - it could be easy enough to make a terrible mistake with the thrusts!
The reason I mention it is - that someone (no - not me!) recently ruined a very fancy Mini engine by doing just that. The thrust washers seized against the crank and welded to it - and then proceeded to rotate with the crank, ruining the block as they did so...........

Post by **Mick_Anik** » Wed Nov 04, 2009 7:56 pm

Yep....engine out is always fun! You can clean it up, paint it, reduce any leaks from it, check the clutch and release bearing, clean and paint around the now-accessible chassis areas.

Post by **SvMinor** » Wed Nov 04, 2009 9:48 pm

I havent had the centre main bearing out yet so I dont know what the crank looks like,The reason I got a new set of bearings was the previous owner said they may need replacing soon because there is a bit of a rattle (not much though) on startup.
What else should I do when I take the engine out.
Two things im worried about,
Will there be a risk of getting an airlock and blowing the head?

Will I be able to replace the timing chain my self without have to get a mechanic to do it and set the timing also?

Hope this makes sense.

Cheers Mark

Post by **bmcecosse** » Wed Nov 04, 2009 10:25 pm

" risk of getting an airlock and blowing the head? " - NO!
" replace the timing chain my self " - It's easy pasy - don't panic!

Any rattle is likely to be from the big-ends -these can easily be renewed with the sump off - have you opened up any of them ? If you really want to exposre the mains - then remove the centre main cap - not carefully which round it is fitted as you take it off, and note how the thrust washers are fitted! Then let's see a picture of the shell.
Note - that you don't know what size the mains (or big-ends) are! So you can't buy new bearings until you check what's in there already!

Post by **SvMinor** » Wed Nov 04, 2009 10:34 pm

Ill try taking the centre 1 out tomorrow evening and post a pic.
Roy It seems like I have to take the engine out then,and forget about trying it with engine still fitted.

Cheers Mark

Post by **bmcecosse** » Wed Nov 04, 2009 10:37 pm

No - don't rush in to that - let's see the bearings first! Maybe nothing much wrong! open up the centre main - and one big-end - and post up pics.

Post by **SvMinor** » Wed Nov 04, 2009 10:40 pm

Ok will do Roy Thanks

Post by **SvMinor** » Thu Nov 05, 2009 10:57 pm

A pic of the centre main bearing and the crankshaft,

Cheers Mark<br>

<br>

Post by **mike.perry** » Thu Nov 05, 2009 11:34 pm

So you bought a set of bearings because the last owner said so.
How do you know what size bearings you need if you haven't had the caps off?

Post by **SvMinor** » Thu Nov 05, 2009 11:37 pm

Because I was told its the original engine in the car,So I got standard ones,Bull motif will change if wrong!